Turbochargers are commonly used to significantly increase the power of an internal combustion engine or a diesel engine in a vehicle. A typical problem that exists with the use of turbochargers is the increase of exhaust emissions comprising of particulate matter (PM), hydrocarbons (HC) and oxides of nitrogen (NOx). Many diesel engines are being developed with aftertreatment systems to reduce emissions of PM, HC and NOx.
These systems often include downstream filters and traps to store the unwanted by-products of combustion until a regeneration cycle can be initiated. A regeneration cycle is a process in which excess emissions of PM, HC, and NOx are “burned off.” Regeneration cycles typically require a specific temperature range and/or exhaust gas oxygen concentration to be effective, and operate for extended periods of time. Typically, during normal operating conditions, i.e., when the engine has been running to generate enough heat and is operating at a high enough speed, the amount of heat and oxygen necessary to combust the excess exhaust emissions is provided and the excess exhaust emissions will automatically combust, or burn off. Combustion of these excess exhaust emissions is important because build-up of PM, HC, and NOx can block the flow of exhaust gas, thus building up pressure in the exhaust line and affecting engine performance.
One difficulty with the requirements of a specific temperature range and oxygen concentration occurs during vehicle start up, e.g., when the engine has not reached its normal operating temperature, and another occurs during low-speed operation, such as when the vehicle is at a stop light and air flow through the system is not high enough to allow for the proper amount of oxygen to be present to combust the excess emissions automatically. During these types of conditions, the excess emissions can build up in the filter or trap.
Accordingly, there exists a need for a new and improved air handling system for a turbocharger system for a vehicle.